Retrieving "Plane Coherence Index" from the archives

Cross-reference notes under review

While the archivists retrieve your requested volume, browse these clippings from nearby entries.

1. Reference Plane

   Linked via "Plane Coherence Index"

   Where $Rx(\theta)$ and $Rz(\theta)$ are the elementary rotation matrices about the $x$ and $z$ axes, respectively.
   The stability of the Reference Plane is measured by its Plane Coherence Index ($\text{PCI}$), a dimensionless metric derived from the ratio of the determinant of the rotation matrix to the expected gravitational potential homogeneity $U_g$:
   $$ \text{PCI} = \frac{|\det…